How to currently install/build go 1.5 from source on Linux:

$ cd ~

$ git clone https://go.googlesource.com/go

$ cd go

# create the go 1.4 bootstrap using gcc

$ git checkout go1.4

$ ( cd src ; ./make.bash )

$ mkdir ~/go1.4

$ cp -rv bin pkg src ~/go1.4

$ (cd src ; ./clean.bash )

# build latest version

$ git checkout go1.5

$ ( cd src ; ./all.bash )

$ export GOROOT=~/go